It has previously been recognized that water flow through an ordinary household residential unit system is intermittent and that normal needs of the household are met by flows rarely exceeding periods of time measured in minutes. Water requirements for dish and clothes washing appliances are normally satisfied with interval water flows of two or three minutes and tub and shower bathing rarely requires a flow of water in excess of 10 minutes. Thus, when water flows continuously through the system for an extended period, say one or two hours, this is usually abnormal and is an indication that there is a leak in the system or someone or something has neglected to close an outlet valve. And, of course, such abnormal flow is highly undesirable because flooding of portions of the household can result in considerable damage to the structure and to its contents.
Prior inventors have devised water shut-off systems in which a valve was closed to terminate the flow of water into the household if there occurred a period of continuous flow of water exceeding a predetermined period of time. For example, Donald C. Aldrich in his U.S. Pat. No. 4,589,435, granted May 20, 1986 for "WATER SHUTOFF VALVE", discloses a valve for terminating flow of water in a residence in response to continuous flow of water therethrough for a predetermined period of time. The apparatus disclosed, however, employs fairly expensive components, such as a disk gate valve and an electronic sensor probe and circuit. The apparatus there disclosed exhibits the further disadvantage of allowing the water to again commence flowing if power is interrupted after shut off even though the leak in the system may not have been repaired.
U.S. Pat. No. 4,518,955, granted May 21, 1985 to Knut Meyer for "METHOD AND APPARATUS FOR DETECTING LEAKAGE IN A FLUID CONDUIT SYSTEM", discloses a very complex flow detection system utilizing a microcomputer to monitor the time flow takes place, the duration of the detected flow, the intensity of the detected flow, and information about what fluid drains of the conduit system are closed. This system simply is uneconomical for an ordinary household.
And Van de Moortele in his U.S. Pat. No. 4,522,229, granted June 11, 1985 for "SAFETY DEVICE FOR WATER-PIPES", discloses a completely hydromechanical safety device for terminating unwarranted water flow. Again, the device appears to be too complex and costly for household use.
There continues to be a need for an inexpensive, but reliable, system and apparatus for shutting off the flow of water in a residence in the event abnormal flow conditions are encountered.